Weird feedneck problem help please!

I have tried everything but can't figure out why my feedneck will not lock on to my rotor. It's a dm12 by the way and my feedneck wil not tighten enough to get my rotor to stay. If you have any help please let me know either on here or through pm.

I have tried everything but can't figure out why my feedneck will not lock on to my rotor. It's a dm12 by the way and my feedneck wil not tighten enough to get my rotor to stay. If you have any help please let me know either on here or through pm.